Temperature-sensitive effects of potassium channel openers on isolated guinea pig myocardium and aorta.
The effects of K+ channel openers, NIP-121, cromakalim, and pinacidil, on isolated myocardium and aorta were investigated at two different temperatures, 23 degrees C and 37 degrees C. In right ventricular myocardium, NIP-121 shortened the action-potential duration with little influence on other action-potential parameters at 37 degrees C, but not at 23 degrees C. In whole-cell clamped ventricular myocytes, NIP-121 induced a glibenclamide-sensitive outward current at 37 degrees C but not at 23 degrees C. No difference in tissue adenosine triphosphate (ATP) concentration was detected between ventricular myocardia incubated at 37 degrees C and at 23 degrees C. In aortic preparations precontracted with norepinephrine, NIP-121, cromakalim, and pinacidil produced endothelium-independent relaxation at 37 degrees C, which was antagonized by glibenclamide. The vasorelaxant effects were greatly reduced at 23 degrees C. Thus we demonstrated that the effects of K+ channel openers on the myocardium and vascular smooth muscle are temperature sensitive.
Saito
W
W
Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Funabashi, Chiba, Japan.
Noguchi
K
K
Okazaki
K
K
Matsuda
T
T
Kato
Y
Y
Tanaka
H
H
Shigenobu
K
K
D000200:Action Potentials / Q000187:drug effects; D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects*; D019806:Cromakalim / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects; D005905:Glyburide / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000737:chemistry / Q000187:drug effects*; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D020110:Pinacidil; D010880:Piperidines / Q000494:pharmacology; D015221:Potassium Channels / Q000819:agonists* / Q000187:drug effects; D013696:Temperature; D014665:Vasodilator Agents / Q000494:pharmacology*
D006146:Guanidines; D010069:Oxadiazoles; D010880:Piperidines; D015221:Potassium Channels; D014665:Vasodilator Agents; D019806:Cromakalim; D020110:Pinacidil; C070366:NIP 121; D000255:Adenosine Triphosphate; D005905:Glyburide; D009638:Norepinephrine